Despite the fact that alpha- and beta-interleukin-1 molecules show limited amino acid homology (Auron, P. E. et al. [1985] J. Mol. Cell Immunol. 2:169-177; Webb, A. C., L. J. Rosenwasser, P. E. Auron [1987] In: Recombinant Lymphokines and Their Receptors, S. Gillis, ed., Marcel Dekker, Inc., New York, pp. 139-158), the proteins bind to the same membrane receptor protein (Dower, S. K. et al. [1986] Nature 324:266-268; Kilian, P. L. et al. [1986] J. Immunol. 136:4509-4514), which has recently been cloned (Sims, J. E. et al. [1988] Science 241:585-588). Human IL-1.beta. protein is synthesized as a 31,000 dalton precursor protein (proIL-1.beta.; 269 amino acids) which binds receptor specifically and has relatively low, but distinct biological activity (Jobling, S. A. et al. [1988] J. Biol. Chem. 263:16732-16738). ProIL-1.beta. is processed by undefined mechanisms to generate the mature protein (IL1(117-269 )), which has maximal biological activity. The numbering system used here is based upon the 269-amino acid unprocessed proIL-1.beta. precursor molecule (Jobling et al., 1988; Auron, P. E. et al. [1984] Proc. Natl. Acad. Sci. USA 81:7907-7911). The processed "mature" form of IL-1.beta. corresponds to positions 117-269. The crystal structure of human IL-1.beta. (Priestle, J. P., H. P. Schar, M. G. Grutter [1988] EMBO J. 7:339-343) has been described as a tetrahedron with edges formed by antiparallel .beta.-strands, but the amino acids which interact with receptor have not been defined. It is very likely that the biological activity of IL-1.beta. is tightly linked to the structural integrity of the protein molecule, for deletion of amino acids from the mature protein is accompanied by severe diminution of bioactivity. Several groups have introduced point mutations in an attempt to probe receptor ligand interactions (Jobling et al., 1988; Dechiara, T. M. et al. [1986] Proc. Natl. Acad. Sci. USA 83:8303-8307; Mosley, B., S. K. Dower, S. Gillis, D. Cosman [1987] Proc. Natl. Acad Sci. USA 84:4572-4576). Huang et al. (Huang, J. J. et al. [1987] FEBS Letters 223:294-298) reported that the biological activity of IL-1.beta. was increased four- to seven-fold by changing the native NH.sub.2 -terminal sequence from ala-pro-val-arg-ser to thr-met-val-arg-ser; however, further alteration of arginine.sub.120 to generate thr-met-val-glu-ser effectively abolished bioactivity. Circular dichroism data demonstrated no major structural differences among the proteins. Gronenborn et al. (Gronenborn, A. M., P. T. Wingfield, H. F. McDonald, U. Schmeissner, G. M. Clore [1988] FEBS Letters 231:135-138) mutated IL-1-alpha histidine and tryptophan residues without effect upon receptor binding affinity, while MacDonald et al. (MacDonald, H. R. et al. [1986] FEBS Letters 209:295-298) reported IL-1 histidine muteins with 2-100 fold less competitive binding activity than the wild-type protein. Although receptor binding affinity and bioactivity are, in general, correlated, the relationship is apparently not always direct.